Human skin consists of two major layers, the dermis and the epidermis. The dermis is the thicker inner layer. It is the layer which provides strength, elasticity and thickness to the skin. The main cell type of the dermis is the fibroblast, which is responsible for synthesis and secretion of dermal matrix components such as collagen, elastin and glycosaminoglycans. Collagen provides strength, elastin the elasticity, and glycosaminoglycans the moistness and plumpness of the skin. With ageing, the thickness of the dermal layer is reduced and this is believed to be partially responsible for the formation of wrinkles in ageing skin.
The top layer of human skin, the epidermis, provides a barrier to the external environment and is composed of many different cell types including keratinocytes, melanocytes and langerhan cells. Keratinocytes are the major cell type of the epidermis (75-80% of the total number of cells in the human epidermis).
Changes in the skin associated with menopause, such as dryness, loss of elasticity, thinning, wrinkles, etc., are attributed to lack of estrogen production. Estrogen therapy prevents, slows down, or reverses many of the changes associated with ageing. Some of the effects of estrogen on the skin include: increase in skin thickness, disappearance of fine wrinkles, increase of the mitotic rate of the epidermis, stimulation of collagen turnover, increases in the production of hyaluronic acid, and synthesis of glycosaminoglycans by the fibroblasts.
While topical estrogen will alleviate wrinkles and other problems associated with aging, such therapy is typically inappropriate due to systemic absorption of the hormone and the corresponding pharmacological effects. A need in the art exists for synthetic estrogens suitable for topical administration to alleviate wrinkles.